Not all the time, but I keep getting random loads, especially whites, where the clothes come out the dryer with 1-2 splatters of small black spots. I have a top loader washer and a dryer. The dryer is starting to squeak during use. Could this be bearing grease? I don't think it's mold as I've left wet paper towels in the area and they don't get moldy after a day. If it is bearing grease, is it fixable or do I have to buy new units?